Method to treat geothermal fluid streams

Abstract

An integrated system of non-condensable gas (NCG) and condensate treatment allows geothermal power plant condensate and non-condensable gas effluent streams containing H2S and ammonia to be commercially useful for more than for cooling tower makeup. In the preferred embodiment, the pH of the condensate is increased by adding ammonia and the pH increased stream is contacted with NCG to scrub and oxidize the H2S constituent of the NCG. By reducing the pH, the condensate or aqueous stream mixture can also be used to further transfer ammonia from the non-condensable gas stream to the aqueous stream, enriching the stream for use as a fertilizer/irrigation water mixture. If other commercial uses are desired for the mixture and/or oxidized NCG streams, they can be resin treated to remove the ammonia constituent. With the ammonia and H2S constituents decreased, the condensate may be used for a variety of applications and the NCG can be injected or used as a commercial feed stream. Rejuvenation of the resin may be accomplished by recycling and purging with the treated NCG. The effluent purge gas may be used to further enrich irrigation waters. A nearly total elimination of all emissions from the geothermal power is thereby made possible.

What is claimed is: 
     
       1. A process for treating geothermal steam stream comprising H 2  O, H 2  S, and ammonia or ammonium ion constituents, said process comprising: condensing less than all of said geothermal steam stream at a first pressure, producing a non-condensed gas stream and a condensate liquid stream, said non-condensed stream comprising a portion of said H 2  S and ammonia or ammonium ion constituents and said condensate stream comprising the remaining constituents;   increasing the pressure to a second pressure on said non-condensed stream;   adding an H 2  S reactant to at least a portion of the pressurized non-condensed stream in an amount sufficient to react with a substantial amount of the H 2  S therein, forming a reacted vapor stream; and   contacting at least a portion of said reacted vapor stream with an absorptive material for removing at least a portion of said ammonia or ammonia ions, thereby forming a treated vapor stream wherein said contacting step also comprises contacting at least a portion of said reacted vapor stream with at least a portion of said condensate stream, said contacted condensate stream forming an ammonia- or ammonium ion-enriched aqueous stream suitable for irrigation of crops.   
     
     
       2. The process of claim 1 wherein said process also comprises the steps of: increasing the pH of said condensate stream portion prior to said contacting step; and   removing a substantial amount of said H 2  S constituent from the pH-increased condensate stream portion to form a pretreated condensate stream prior to said contacting step.   
     
     
       3. The process of claim 2 wherein said step of contacting also condenses a portion of said H 2  O constituent and said contacting is sufficient to significantly decrease the ammonia or ammonium ion concentration in said treated vapor stream. 
     
     
       4. The process of claim 3 which also comprises the step of converting at least a portion of the energy of said geothermal steam stream to work prior to said condensing step. 
     
     
       5. The process of claim 1 wherein said contacting step comprises: first contacting at least a portion of said reacted vapor stream against an adsorbent and adsorbing at least a portion of said ammonia or ammonium ion constituent of said reacted vapor stream to produce said treated vapor stream; and   periodically contacting at least a portion of said treated vapor stream and an aqueous stream against said adsorbent, transferring at least a portion of the adsorbed ammonia or ammonium ions to said periodically contacted streams to produce a regenerant stream.   
     
     
       6. The process of claim 5 which also comprises: blending an aerated water stream with at least a portion of said condensate stream prior to said transferring step;   first mixing at least a portion of said regenerant stream with at least a portion of said condensate stream to form a mixed stream; and   second mixing at least a portion of said mixed stream with at least a portion of said condensate stream after said transferring step.   
     
     
       7. The process of claim 6 wherein said reactant is selected from the group consisting of oxygen, chlorine, bromine, ozone, iron chelates, trichloroisocyanuric acid, sulfur dioxide, and mixtures thereof, said process also comprising the step of irrigating an agricultural crop with at least a portion of said mixed stream. 
     
     
       8. The process of claim 7 which also comprises steps of: second contacting at least a portion of said condensate stream against an ammonia or ammonium ion adsorbent to form a treated condensate stream;   periodically contacting at least a portion of said treated vapor stream and said treated condensate stream against said adsorbent, transferring at least a portion of said absorbed ammonia or ammonium ions to the periodically contacted streams to produce a second regenerant stream; and   mixing at least a portion of said second regenerant stream with at least a portion of said condensate stream.   
     
     
       9. The process of claim 8 which also comprises the step of blending at least a portion of said treated condensate stream with a second aqueous source stream not derived from a geothermal source, forming a blended aqueous mixture. 
     
     
       10. The process of claim 9 wherein said second aqueous source is a ground water which contains contaminants making it substantially unsuitable for consumptive commercial use. 
     
     
       11. The process of claim 10 which also comprises the step of supplying at least a portion of said blended mixture to a consumptive commercial use. 
     
     
       12. The process of claim 11 wherein said consumptive commercial use is a potable water delivery system. 
     
     
       13. The process of claim 12 wherein said adding step also comprises injecting a reactant into at least a portion of said condensate stream. 
     
     
       14. The process of claim 13 which also comprises the steps of: evaporating at least a portion of said treated condensate stream in a cooling tower to produce at evaporate stream; and   supplementing said condensate stream with at least a portion of said evaporate stream prior to said second contacting step.   
     
     
       15. A process for treating geothermal steam stream comprising H 2  O, H 2  S, and ammonia or ammonium ion constituents, said process comprising: condensing less than all of said geothermal steam stream at a first pressure, producing a non-condensed gas stream and a condensate liquid stream, said non-condensed stream comprising a portion of said H 2  S and ammonia or ammonium ion constituents and said condensate stream comprising the remaining constituents;   increasing the pressure to a second pressure on said non-condensed stream;   adding a H 2  S reactant to at least a portion of the pressurized non-condensed stream in an amount sufficient to react with a substantial amount of the H 2  S therein, forming a reacted vapor stream;   contacting at least a portion of said reacted vapor stream with an absorptive material for removing at least a portion of said ammonia or ammonia ions, thereby forming a treated vapor stream wherein said contacting step comprises contacting at least a portion of said reacted vapor stream with at least a portion of said condensate stream, wherein said contacting step comprises:   first contacting at least a portion of said reacted vapor stream against an adsorbent and adsorbing at least a portion of said ammonia or ammonium ion constituent of said reacted vapor stream to produce said treated vapor stream; and   periodically contacting at least a portion of said treated vapor stream and an aqueous stream against said adsorbent, transferring at least a portion of the adsorbed ammonia or ammonium ions to said periodically contacted streams to produce a regenerant;   blending an aerated water stream with at least a portion of said condensate stream prior to said transferring step;   first mixing at least a portion of said regenerated stream with at least a portion of said condensate stream to form a mixed stream;   second mixing at least a portion of said mixed stream with at least a portion of said condensate stream after said transferring step, wherein said reactant is selected from the group consisting of oxygen, chlorine, bromine, ozone, hydrogen peroxide, iron chelates, trichloroisocyanuric acid, sulfur dioxide, and mixtures thereof;   irrigating an agricultural crop with at least a portion of said mixed stream;   second contacting at least a portion of said condensate stream against an ammonia or ammonium ion adsorbent to form a treated condensate stream;   periodically contacting at least a portion of said treated vapor stream and said treated condensate stream against said adsorbent, transferring at least a portion of said absorbed ammonia or ammonium ions to the periodically contacted streams to produce a second regenerant stream;   mixing at least a portion of said second regenerant stream with at least a portion of said condensate stream;   blending at least a portion of said treated condensate stream with a second aqueous source stream not derived from a geothermal source, forming a blended aqueous mixture, wherein said second aqueous source is a ground water which contains contaminants making it substantially unsuitable for consumptive commercial use;   supplying at least a portion of said blended mixture to a consumptive commercial use, wherein said consumptive commercial use is a potable water delivery system and wherein said adding step also comprises injecting a reactant into at least a portion of said condensate stream;   evaporating at least a portion of said treated condensate stream in a cooling tower to produce an evaporate stream;   supplementing said condensate stream with at least a portion of said evaporate stream prior to said second contacting step; and   supplying at least a portion of said treated vapor stream as a feed to a commercial CO 2  consuming process.   
     
     
       16. The process of claim 15, wherein said CO 2  consuming process produces dry ice. 
     
     
       17. The process of claim 16 which also comprises injecting a non-heavy metal inhibitor into said treated condensate stream portion prior to said evaporating step, wherein said inhibitor comprises a phosphate and the amount of said inhibitor is less than 50 percent of the amount of inhibitor which would have been injected into said condensate stream if it had been use instead of said treated condensate stream. 
     
     
       18. The process of claim 17 wherein said condensate stream also comprises an arsenic constituent and said process also comprises contacting said condensate stream against an arsenic-adsorbing resin. 
     
     
       19. The process of claim 17 wherein said condensate stream also comprises a boron constituent and said process also comprises the steps of: third contacting at least a portion of said condensate stream against a boron adsorbent, producing a boron-treated condensate stream;   periodically contacting an acidic aqueous stream against said boron adsorbent and transferring at least a portion of the adsorbed boron to said acid stream to produce a third regenerant stream; and   evaporating at least a portion of said third regenerant stream.   
     
     
       20. The process of claim 19 wherein said first contacting is accomplished by countercurrent flows in a packed vessel. 
     
     
       21. The process of claim 20 wherein said step of increasing the pressure utilizes an ejector and comprises supplying said vapor stream as a motive fluid for operating said ejector. 
     
     
       22. The process of claim 21 wherein said step of increasing pressure produces a non-condensed stream pressure of at least 1 atmosphere. 
     
     
       23. The process of claim 22 wherein said contacting occurs at a vapor-liquid volume ratio of greater than 0.8. 
     
     
       24. The process of claim 23 wherein said contacting occurs at a temperature in the range from about 10° to 65° C. 
     
     
       25. A process for treating a condensate liquid effluent and a non-condensate gas effluent from a condenser of a geothermal process, said non-condensate effluent comprising nitrogen and sulfur constituents, said process comprising: contacting at least a portion of said non-condensate effluent with an oxygen-containing aqueous liquid feed wherein said contacting is sufficient to oxidize a substantial amount of said sulfur constituent in said non-condensate portion;   oxidizing at least a portion of said sulfur constituent of said condensate effluent;   removing at least a portion of said nitrogen constituent from at least a portion of said non-condensate effluent;   transferring at least a portion of said removed nitrogen constituent to said oxidized condensate, forming an enriched condensate; and   irrigating plants with said enriched condensate.   
     
     
       26. The process of claim 25 wherein said condensate effluent also comprises boron and arsenic constituents and said process also comprises: removing at least portion of said boron constituent;   removing at least a portion of said arsenic constituent;   evaporating at least a portion of said condensate after said removing steps; and   irrigating plants with at least a portion of said condensate after said evaporating step.   
     
     
       27. A process for treating geothermal steam stream comprising H 2  O, H 2  S, and ammonia or ammonium ion constituents, said process comprising: condensing less than all of said geothermal steam stream at a first pressure, producing a non-condensed gas stream and a condensate liquid stream, said non-condensed stream comprising a portion of said H 2  S and ammonia or ammonium ion constituents and said condensate stream comprising the remaining constituents;   increasing the pressure to a second pressure on said non-condensed stream;   adding an H 2  S reactant to at least a portion of the pressurized non-condensed stream in an amount sufficient to react with a substantial amount of the H 2  S therein, forming a reacted vapor stream;   contacting at least a portion of said reacted vapor stream with an absorptive material for removing at least a portion of said ammonia or ammonia ions, thereby forming a treated vapor stream wherein said contacting step also comprises contacting at least a portion of said reacted vapor stream with at least a portion of said condensate stream; and   supplying at least a portion of said treated vapor stream as a feed to a commercial CO 2  consuming process.